The invention relates generally to power or hand tool bit holders, variously known as "auxiliary chucks", "chucks", or "adapters", for removably receiving tool bits, such as fastener drivers, drill bits, or the like, for rotation therewith when the power tool is actuated or the hand tool is manually rotated. More particularly, the present invention relates to chuck assemblies or adapters configured for rapid and easy insertion and removal of a tool bit.
Auxiliary chucks for power and hand tools have become increasingly common, especially as the need and desirability of wider versatility in the use of power tools and hand tools has increased. Such auxiliary chucks allow the hand or power tool to be used with any of a number of interchangeable bits. This, in turn, has resulted in demands for greater speed, convenience and ease of insertion and removal of tool bits from such chucks.
In one exemplary type of such conventional quick-release chucks, one or more detented balls are positioned within a hollow, barrel-shaped tool bit holder body and are resiliently biased into engagement with a circumferentially-extending groove or recess on the shank of the tool bit. Although this basic design has performed well, chuck assemblies or bit holders of this type have been found to be inordinately expensive and difficult to manufacture due to the relatively large number of parts required, as well as frequently requiring the operator to actuate a sleeve, collar or other component part during both the insertion and the removal of the tool bit.
Accordingly, the present invention seeks to provide a simple, relatively inexpensive quick-acting chuck assembly or bit holder that requires the operator to actuate its components only upon tool bit removal. A "snap-in" type of chuck assembly is provided for a drill, driver, or other rotary hand or powered tool, with the chuck assembly including a generally cylindrical body having a hex shank at its inner or rearward end for rotatable attachment to a drill or driver. A hollow cylindrically-stepped retraction collar or sleeve is slidably disposed for movement in an axial direction on an intermediate portion of the body, and an outer retaining collar is fixed both axially and circumferentially to the outer end of the body for rotation therewith. The outer retaining collar has a central opening, and the body has a coaxial hollow hex socket or bore formed therein, both of which open toward the outer or forward end of the chuck, in order to allow a tool bit to be inserted into the chuck assembly for rotation therewith.
An angular slot, extending in a radially-inward and axially-forward direction, is formed in the body, providing communication between the radially outer periphery of the body and the internal hollow hex bore. A coil spring surrounds the body and is disposed inside the retraction collar, with the inner or rearward end of the spring engaging a shoulder on the body and with the outer or forward end resiliently biasing the retraction collar forwardly and biasing a retaining clip radially inwardly and axially forwardly toward the bottom or inner end of the angular slot where it intersects with the body's hollow hex bore.
As a tool bit is snapped into the chuck's socket, this retaining clip, which is preferably of a generally U-shaped configuration, is forced to slide rearwardly and radially outwardly in the angular slot, against the bias of the coil spring, in order to allow the bit to be inserted. Once the bit is fully seated in the hex socket, the base portion of the U-shaped clip is resiliently urged back down toward the bottom of the angular slot where it engages the circumferential recess formed on the hex shank of the bit, thus retaining the bit in the hex socket or bore where it can be rotatably driven by the drill or driver to which the chuck assembly or bit holder is attached. The tool bit is removed from the chuck assembly by the operator sliding the retraction collar axially rearwardly along the body, thus compressing the coil spring to allow the retaining clip to retract back up the angular slot and release the tool bit as the tool bit is pulled from the hex socket.
In preferred forms of the present invention, the U-shaped spring clip is directly engaged and biased by the coil spring, and both of its legs are curved inwardly around a portion of the chuck's body so that the clip is self-retaining. In this configuration both the curved legs extend around the body to locations on an opposite side of the body's axis from the clip's base in the angular slot. In this way, the direct contact of the clip with the coil spring is directed axially generally through the center of the coil spring so as to keep the coil spring coaxially aligned with the body and thus to minimize off-axis "cocking" of the coil spring.
Also, in a preferred form of the invention, the corners of the U-shaped clip (at the intersections of the curved legs with the straight base) serve as "stops" for the retraction collar sleeve, by engaging its internal hollow bore as the clip is retracted up the angular slot, in order to prevent over-retraction and consequent jamming of the retraction collar.
In addition, the preferred coil spring can be provided with at least one of its bights, at either the forward or rearward ends, or at both ends, being axially collapsed in order to form one or more "dead coils" at the coil spring end (or ends). This feature allows the coil spring to more flatly abut the spring clip at the forward end of the coil spring, and/or more flatly engage the stepped portion of the body at the rearward end of the coil spring, thus keeping the coil spring and the retraction collar properly coaxially aligned with the body.
Finally, in order to facilitate the ease and speed of insertion or removal of the tool bit, and to greater facilitate the chuck's ergonomics, the retraction collar is preferably formed with one or more discontinuities on its radially outer periphery, preferably in the form of circumferentially-extending ribs, to which a polymeric cover is attached and engagingly retained on the periphery of the retraction collar.
Preferably, a polymeric cover is press-fit over parallel annular ribs formed on the exterior surface of the retraction collar. Ideally, the polymeric cover is formed in a two-shot process, in which an outer layer of thermoplastic elastomer is molded over a copolymer thermoplastic base layer of a contrasting color, such that suitable raised icons, identifiers, logos, or trademarks protrude through the outer layer and are flush with the outer surface of the cover. In the preferred embodiment, the outer layer is black, and the protruding raised portions of the base layer spell out the trademark DeWALT.RTM. in yellow letters. As a result, the operator experiences a "soft-grip" tactile sensation that provides an exceptional grip on the chuck assembly, and which further provides a durable, eye-catching display of the manufacturer's livery and identifiers .